Polymer Object Optical Fabrication Process

ABSTRACT

High-volume mass-production and customization of complex three-dimensional polymer and polymer-derived-ceramic microstructures are manufactured in a single step directly from three-dimensional computer models. A projection based non-degenerate two-photon induced photopolymerization method overcomes the drawbacks of conventional one and two-photon fabrication methods. The structure includes dual, synchronized, high-peak power, pulsed femtosecond and picosecond lasers combined with spatial light modulation. Applications include high-resolution rapid prototyping and rapid manufacturing with an emphasis on fabrication of various Micro-Electro-Mechanical Systems (MEMS) devices, especially in the area of MEMS packaging.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to currently pending U.S. provisionalpatent application 60/737,365 entitled “Polymer Object OpticalFabrication,” filed Nov. 17, 2005 by the same inventor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates, generally, to microstereolithography. Moreparticularly, it relates to a non-degenerate two-photon approach toprojection microstereolithography.

2. Description of the Prior Art

Microstereolithography enables the manufacturing of small and complexthree-dimensional components from plastic materials.

One-photon polymerization is a process that causes a photo-initiatormonomer concentration to induce a photochemical reaction, which in turncauses the concentration to cross-link and solidify. The process is thebasis for most commercially available stereolithography systems.

Two-photon polymerization is a technique for the fabrication of threedimensional micron and sub-micron structures. A beam of ultra fastinfrared laser is focused into a container holding a photo-sensitivematerial to initiate the polymerization process by non-linear absorptionwithin the focal volume. By focusing the laser in three dimensions andmoving the laser through the resin, a three dimensional structure can befabricated. Two-photon microstereolithography enables three dimensionalprocessing as well as high complexity microfabrication.

Researchers have demonstrated experimental two-photon micro/nanostereolithography but have not incorporated projection technology intothe two-photon fabrication process and have not combined non-degeneratetwo-photon photopolymerization based on intersecting femtosecond pulsedprojected images with picosecond pulsed laser light sheet at the focalplane. Existing two-photon stereolithography techniques enable unlimitedcomplexity in the part geometries that can be fabricated by polymerizinga single focal volume voxel inside the bulk volume of photopolymer viathe two-photon absorption process. However, these systems are limited inthe volume that can be fabricated in a timely manner due to thepoint-by-point fabrication approach. These systems also requireultra-precision control of translation or mirror steering systems togenerate parts of adequate resolution at the micro scale. The trend ofeverincreasing two-photon absorbing cross-sections of photoinitiatorsexplicitly tailored for two-photon processes in recent years suggeststhat the speed of the scanning mirror systems will also present somelimitations in two-photon stereolithography now and in the future.

One-photon based microstereolithography techniques fabricate in asurface layer-by-layer approach that ultimately limits the process torapid prototyping and some small production runs of micropolymerstructures. The surface layer-by-layer approach also limits thegeometries of objects that can be fabricated due to surface tension orrelease layer issues, and requires an extensive network of supportstructure to be digitally inserted into three-dimensional models viasupport structure insertion algorithms. All of these factors limit thefabrication process and slows the overall throughput of micropolymerstructures.

There also exists a gap between prototyping of complex micro geometriesusing microstereolithography and mass production of complex geometries.The ideal microstereolithography device would allow any complexity ingeometry, need no support structure, and enable rapid prototyping,mass-production, and mass customization from a single machine.

Two-photon absorption can occur in two forms: degenerate andnon-degenerate. The process is known as degenerate if the photonsabsorbed are of the same wavelength. The process is known asnon-degenerate when the photons absorbed are of two-differentwavelengths.

Nearly all of the research conducted on two-photon polymerization hasbeen limited to degenerate schemes using a single focused laser beam.Non-degenerate two-photon polymerization, using two lasers of twodifferent wavelengths, increases set-up costs, requires optical hardwarehaving a more complex configuration and dual laser pulsesynchronization. However, a non-degenerate configuration offers distinctadvantages that have an impact on the overall throughput and versatilityof the fabrication system. Non-degenerate systems offer more controlover the geometry of the reaction volume due to the fact that thereaction volume is confined only to the overlapping beams of theappropriate wavelengths.

The rate of degenerate two-photon absorption, in a dual intersectingbeam degenerate two-photon configuration, increases where the two beamsintersect but photo-absorption also occurs in the light path prior tothe desired reaction volume if the beams enter a sample already tightlycollimated, or at a low numerical aperture. This configuration causessome two-photon absorption (TPA) in the beam delivery paths with anincrease in absorption occurring at the intersection of the two beams,thus limiting the overall irradiance that is deliverable to the desiredfabrication volume. This situation also limits the achievable speed ofphotopolymerization and feature size resolution. For two-photonpolymerization photon absorption in the beam's delivery path is anundesired effect and is solved by implementing a focusing scheme with ahigh numerical aperture. The increase in the probability for absorptionto occur as the beam approaches the focal point reduces the possibledegenerate configurations to designs that have a high numerical apertureobjective lens.

Thus there is a need for a two-photon projection microstereolithographymethod that incorporates a non-degenerate two-photon approach toprojection micro stereolithography but which is not subject to thelimitations of the known methods.

However, in view of the art considered as a whole at the time thepresent invention was made, it was not obvious to those of ordinaryskill in this art how the identified needs could be met.

SUMMARY OF THE INVENTION

The long-standing but heretofore unfulfilled need for improvements inmicrostereolithography is now met by a new, useful and nonobviousinvention.

The novel two-photon projection microstereolithography processincorporates an innovative non-degenerate two-photon approach toprojection microstereolithography. More particularly, non-degeneratetwo-photon absorption enables single-step, all digital, mass fabricationof micro-polymer or polymer-derived-ceramic structures of virtually anythree-dimensional geometry directly from computer model design files.This single-step fabrication process is for convenience referred to asthe Polymer Object Optical Fabrication (POOF) process, which acronymsuggests the extremely fast microfabrication of three-dimensional micropolymer structures of unlimited complexity in part geometry includingvirtually any aspect ratio desired.

The POOF process further evolves the known stereolithography process bytaking a projection-based, non-degenerate two photon inducedphotopolymerization (TPIP) approach to stereolithography. Incorporatinga spatial light modulator such as Texas Instrument's Digital LightProcessor (DLP™) projection technology into the two-photon fabricationprocess introduces a highly parallel approach to microstereolithographythat substantially reduces or eliminates the need for support structure,provides unlimited part geometrical complexity (within a finite range ofmicro resolution smallest feature sizes) in resulting parts, andprovides the optical and mechanical configuration that enables rapidprototyping, high-volume mass-production, and mass-customization ofmicro polymer and micro-polymer-derived-ceramic structures from a singlemachine in a single step.

This process is used in conjunction with photoinitiators with a hightwo-photon absorption cross-section combined with various acrylates,vinyl ethers, epoxies, bio-degradable hydrogels, elastomers, orpolymer-derived-ceramics to make complex microstructures for MicroElectro Mechanical Systems (MEMS) and integrated complexthree-dimensional optical circuitry for MicroOptoElectroMechanical(MOEMS) devices for a wide range of industries. POOF technology will bean integral tool in the development of polymer and ceramic-based MEMSand MOEMS technologies with a special emphasis on packaging fabricationfor current and emerging MEMS and MOEMS devices. The fabricationcapability of the POOF process enables the fabrication versatility andthroughput of micro geometries currently not feasible with existingfabrication techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic side elevational view of a first embodiment;

FIG. 2 is a diagrammatic end view of the FIG. 1 structure;

FIG. 3 is a diagrammatic top plan view of the FIG. 1 structure;

FIG. 4 is a diagrammatic end view of a second embodiment;

FIG. 5 is a diagrammatic side elevational view of the second embodiment;

FIG. 6 is a diagrammatic side elevational view of a third embodiment;and

FIG. 7 is a diagrammatic top plan view of said third embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This invention includes a method for the patterned solidification,desolidification, or modification of the index of refraction of a photoreactive material by non-degenerate two-photon absorption therebyproviding rapid fabrication of three-dimensional micro-structuresdirectly from computer models. The steps of the novel method include:

Placing a medium capable of selective solidification, desolidification,or refractive index modification via non-degenerate two-photonabsorption into a container having at least one optically transparentwindow so that the medium within the container is accessible by laserlight. In the alternative, the entire container may be made of anoptically transparent material;

Providing an array of controllable pixel elements;

Selecting two synchronized pulsed laser sources having respectivewavelengths to induce non-degenerate two-photon polymerization;

Providing an optical projection system for projecting patterned imagesof femtosecond pulsed laser light;

Directing femtosecond laser pulses onto the array of pixel elements, sothat a desired patterned portion of source light travels through thewindow of the container and into the photoreactive material and focusesinside the photoreactive material;

Providing an optical system for producing the sheet of light ofpicosecond pulsed laser light so that sheet has an optimal thinness andflatness;

Aiming the femtosecond patterned light and the picosecond sheet of lightso that they intersect one another orthogonally with the two focalplanes overlapping. More particularly, directing picosecond pulses in athin, flat sheet so that said picosecond pulses intersect with thefemtosecond pulses, such that the thin, flat sheet of picosecond pulsesintersects the source light perpendicular to the projected source fromthe array of pixel elements so that select regions of the photoreactivematerial are cured at the intersection;

Positioning the container and the photoreactive material therewithinrelative to the intersecting focal planes at an angle less than thecritical angle of the container material and photoreactive material;

Monitoring the real-time velocity of the container through the lightintersection region by employing a velocity sensor;

Providing a computer control system that sends electronic data for eachimage pattern to be projected from the controllable pixel element wherethe refresh rate of the controllable pixel array is throttled accordingto the velocity data obtained from the velocity sensor. In thealternative, the feedback could alter the conveyor speed, control thelaser repetition rate, the light path length, or the controllable pixelarray. A finely tuned system may not require feedback;

Providing a computer-executable program for extracting a series ofslices of a three-dimensional computer model data into a seriestwo-dimensional image files that are compatible with the controllablepixel elements;

Sequentially sending the sequence of two-dimensional images extractedfrom the three-dimensional computer model file to the controllable pixelarray, thereby enabling projection of the slices of the computer modelfile into the medium as the medium volume translates through theintersecting focal planes at a velocity determined by the photo reactivecure time of the photoreactive material and the real-time velocityfeedback data; and

Synchronizing overlapping pulses operating at two different wavelengthsthat are of preselected energies to meet the combined energyrequirements necessary to achieve non-degenerate two-photon absorptionin the beam intersection volume within the photoreactive material.

The array of controllable pixel elements may include a spatial lightmodulator and the spatial light modulator may include a plurality ofmirrored surfaces each independently pivotable from a first to a secondposition or state allowing directional control of the area of lightreflecting from each mirror. The spatial light modulator is controlledby digital electronics that modify each mirror state by loading a binaryarray of data. Each bit of data in the binary image array determines thedirectional pivot of the mirror thus providing spatially patternedprojection of laser pulses. The binary array of mirror state data isprovided by two-dimensional slice plane image data that isprogrammatically extracted from a three-dimensional computer model. Thetwo-dimensional slice plane data extracted from the computer model is insome cases an exact two-dimensional cross-section replica of the desiredfabrication geometry and in other cases the extracted slice plane datais processed in such a way as to use the spatial light modulator as adigital programmable holographic grating capable of projecting aholographic image into the medium.

The illuminating pulsed laser light of the spatial light modulator is afemtosecond pulsed laser source.

An optical system couples with the spatial light modulator to form alaser illuminated projector that has an aspheric beam shaping condenserlens placed prior to and directed onto the spatial light modulator, amicromirror array spatial light modulator, and a reducing imager lensplaced post spatial light modulator and focused to intersect sheet oflight. This invention is not limited to a micromirror array spatiallight modulator. There are many types of spatial light modulators andall of them are within the scope of this invention.

The aspheric condenser lens redistributes the Gaussian energydistribution of the femtosecond laser light to form a more even energydistribution across the spatial light modulator and thus across theprojected focal plane, and the projected image is directed into a regionthat will allow intersection with the picosecond light sheet and allowthe medium and windowed container/cuvette to pass through theintersection region.

Alternatively, the optical imager lens can be used to expand or reducethe total area of the projected image thus decreasing or increasing thebuild resolution respectively.

The sheet of light optical system is capable of creating a thin sheet ofpulsed radiance energy from the picosecond source using an asphericbeam-shaping cylindrical lens set placed between the picosecond lasersource and the beam intersection volume or “fabrication plane.” Theaspheric beam-shaping cylindrical lens set redistributes the picosecondlaser light Gaussian energy distribution to form a more even energydistribution across the thin light sheet. The thin sheet of pulsedenergy is directed into the vat perpendicular to the focal plane of thefemtosecond projected image.

Alternatively, the sheet of light optical system can be designed from adiffractive optical element that forms a sheet of light that intersectsthe focal volume of the projected source

The photoreactive material includes a highly efficient two-photonphotoreactive initiator material combined with compatible fast reactingmonomers such as acrylates, vinyl ethers, epoxies, biodegradablehydrogels, elastomers, or polymer-derived-ceramics. The medium may be aliquid resin that is solidified upon exposure to the intersecting beamsthus allowing microstructure fabrication. It may also be a solid that isdesolidified upon exposure to the intersecting beams thus allowmicrostructure fabrication. It may also be a material with thecapability of altering the index of refraction thus enabling thefabrication of waveguides.

The novel POOF process incorporates a spatial light modulator such asTexas Instrument's digital light processor (DLP™) projection technologyinto a two-photon fabrication process. It requires a non-degenerateapproach to the TPIP process due to the geometry of the projected lightentering the bulk volume of the polymer. The POOF process furtherrequires that the projection system be illuminated by a high peak-power,femtosecond, pulsed, laser source operating at a specific wavelength λ₁which projects a series two dimensional slices of a three dimensionalcomputer model.

The pulsed image is projected into the bulk fabrication volume ofphotopolymer material through a reducing imager lens of approximately1.1:1 or greater reduction A high peak-power, nanosecond, pulsed, verythin, flat sheet of laser light operating at a specific wavelength λ₁,orthogonally intersects the pulsed image at the focal plane of theprojection imager lens. At this junction of the femtosecond pulsed imageand the thin sheet of picosecond pulsed light the two differentwavelengths of light, λ₁ and λ₂, will induce non-degenerate TPA thusinitiating the free-radical or cationic TPIP process of an entiredigitally patterned two-dimensional slice of a computer model in eachsynchronized dual pulse intersection. This intersection of femtosecondprojected pulsed images intersecting with picosecond pulsed sheet oflight is a significant feature of the invention.

Non-degenerate two-photon absorption increases the overall complexity ofthe machine design by requiring two synchronized pulsed lasers. However,another advantage in implementing this configuration exists in theversatility to alter the beam intersection geometry. This allowsalteration of the fabricated voxel geometry. Non-degenerate two-photonscheme also enables utilization of lower numerical apertures in atwo-photon polymerization process. This versatility is inherent in thenon-degenerate two-photon absorption process because two-photonabsorption will only occur in the volume of the pulses intersectionwhere the combined irradiance of each beam plays a contribution tomeeting the quadratic irradiance dependence required for TPIP.

To ensure an optimized microstereolithography process capable of highvolume mass production, the projected image is directed into a vat orcuvette at an angle less than the critical angle of the a transparentvat/cuvette wall and the photopolymer material. This criticallyimportant aspect of the POOF configuration meets five crucial conditionsduring the fabrication of the desired object: A) a static focal plane,B) substantially static optical components in the optical path(excluding minute vat vibration), C) constant velocity translation in asingle axis, D) substantially turbulence free photopolymer build volume,and E) an array of up to 4.1 million fabricated voxels digitallyprojected via a high performance spatial light modulator such as theextremely high performance Texas Instrument's Digital Micromirror Device(DMD).

From an optical, mechanical, and software design perspective, meetingthese five important design constraints produces amicrostereolithography process that is optimized for high-speed,high-volume microfabrication. Meeting these design constraints alsoidentifies the overall novelty of the POOF technology in an all digital,high-speed, non-degenerate two photon, projection,microstereolithography device for high-volume 3D microfabrication of anygeometry.

The basic POOF system includes an enclosed transparent vat containing atwo-photon photoinitiator monomer concentration that is meets thecriteria of one-photon optical transparency of each of the POOFprocess's dual synchronized lasers.

The vat is mounted to a low vibration translation system that translatesthe vat at a constant velocity through the fabrication plane where thepulsed image and sheet of light intersect. The DLP™ projection systemprojects a series of high peak power femtosecond pulsed cross-sectionalCAD model slice image at a refresh rate defined by the velocity of thetranslation system and the polymerization rate of the photoreactivematerial. A picosecond pulsed thin sheet of light is synchronized tointersect the projected pulsed image in the focal plane. Because ofnumerical apertures of the light entering the photopolymer volume, thewavelength of light, and the irradiance of the pulsed laser lightneither single beam alone can induce immediate TPIP. A liquid volumegoes in and “POOF,” the three-dimensional part is produced. Thethickness of each fabrication slice is determined by the non-degenerateTPIP dynamics of the spatial thickness of the sheet of light interactingwith the temporal length of the femtosecond projected pixel in thephysical intersection geometry and also by any diffusion of the light asphotopolymerization occurs and the termination coefficient of thepolymer chain during the reaction.

Further empirical exploration of the intersection beam geometries, witheach of the best material candidates, is required to determine theoptimal balance of intersecting femtosecond pulse energy dose andpicosecond pulse energy dose range that will induce non-degenerate TPIPwithout causing thermal damage during the fabrication process whilemaintainging the highest possible throughput of the system.

The POOF process laser systems and optical systems are chosen by meetingthe criteria that TPIP occurs only in the intersection volume of thelaser beams. Exposing the photopolymer material to either the projectedfemtosecond pulsed image of wavelength λ₁ or the picosecond pulsed sheetof light of wavelength λ₂ alone will not induce immediate TPIP. Onlywhere the beam operating at λ₁ intersects with a second beam operatingat λ₂, where λ₁ and λ₂ are of the appropriate combined energies, willthe energies sum to induce immediate TPIP.

The picosecond pulse sheet thickness and collimation is constrained toan irradiance limitation below the irradiance induced damage thresholdof the photopolymer materials. The optimal theoretical light deliverysystem working in conjunction with the optimal chemical and hardwareconfiguration facilitates a process capable of high volume production ofpolymer-based micro-structures with the unprecedented combination ofthree-dimensional complexity, feature size resolution, and volumethroughput. Several conceptual TPIP projection POOF designconfigurations for mass production are depicted in the drawings thatinclude designs for rapid prototyping or rapid manufacturing of polymeror polymer-derived-ceramic microstructures and a design for highresolution rapid prototyping of micro-feature build resolution ofmacrostructures

To fully optimize the overall throughput of this system an optionalhardware addition to the overall system is realized by incorporating amagnet that creates a thin, sheet-like, magnetic field across the pulsedlight intersection region also called the fabrication region. It isknown that photopolymers located in a moderate magnetic field can havean increase in the overall photoefficiency of the photopolymerizationprocess. However, no prior art in the field of stereolithography or TPIPconfigurations has incorporated a thin magnetic field into the focalregion of the incoming light. Increasing the overall photoefficiency ofthe process results in either lower pulse power requirements to achieveTPIP or an increase in the overall fabrication throughput of theprocess.

FIGS. 1-3 depict a typical set-up, which is denoted as a whole by thereference numeral 10. Conveyor system 12 carries container 14 throughthe fabrication region. As mentioned above, at least part of container14 is optically transparent. The depicted conveyor system includes asprocketed belt 16 that makes a continuous path of travel aroundsprocket pulleys 18 a, 18 b that are longitudinally spaced apart fromone another and which are respectively supported by vibration isolationbase members 19 a, 19 b having support legs 20 a, 20 b. Optically flatglass tracks 22 provide a guided path for container 14 through thefabrication region is itself supported by base members 21 a, 21 b andsupport legs 23 a, 23 b.

Of course, the art of machine design includes numerous equivalentstructures for carrying a container along a predetermined path of traveland all of such equivalent structures are within the scope of thisinvention.

The femtosecond pulsed laser is denoted 24 and the picosecond pulsedlaser is denoted 26. The spatial light modulation (SLM) projectionsystem associated with femtosecond pulsed laser 24 is denoted 28 and thefemtosecond pulsed laser 24 illuminated projection optics is denoted 30.

The femtosecond pulsed laser images projected by SLM projection system28 are denoted 32. These images are also referred to as the image sourcelight.

The flat sheet of picosecond pulsed laser light is denoted 34 isilluminated by the picosecond pulsed laser denoted 26 and formed by thesheet of light optics denoted 35.

The intersection where the synchronized laser pulses meet, i.e., whereimages 32 meet flat sheet 34, is denoted 36. Intersection 36 is thefabrication region.

Thin magnet 38 is positioned in an inclined plane and intersectsfabrication region 36.

The structure diagrammatically depicted in FIGS. 4 and 5 differs fromthe structure of FIGS. 1-3 in that no magnet 38 is provided in thisembodiment. In all other respects, the structure is the same asindicated by the reference numerals, which are common to FIGS. 1-5.

A third embodiment is depicted in FIGS. 6 and 7. Most of the functionalparts are the same as in the first two embodiments as indicated by thecommon reference numerals. However, instead of a relatively smallcontainer 14 that contains the photoreactive material, a large vat 40contains said material. Vertical lifting platform 42 is positionedinside said large vat and suitable means are provided for elevating saidplatform 42 in increments that correspond to the vertical height of thefabrication region 36 as the inventive method is performed.

Vat 42 is supported by a dual axis translation system that includesrigid arms 44, 46 disposed at a right angle relative to one another atthe base of vat 42, externally of said vat. Translation of vat 42 alongan x-axis is controlled by arm 44, along a y-axis by arm 46, and along az-axis by vertical lifting platform 42. The z-axis is perpendicular tothe plane of the paper in FIG. 7. In this way the photoreactive materialis moved through fabrication region 36 as vat 40 is translated alongsaid axes under the control of a computer.

It will be seen that the advantages set forth above, and those madeapparent from the foregoing description, are efficiently attained andsince certain changes may be made in the above construction withoutdeparting from the scope of the invention, it is intended that allmatters contained in the foregoing description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween. Now that theinvention has been described,

1. A method for fabricating three-dimensional micro-structures directlyfrom computer models, comprising the steps of: providing a container atleast a part of which is optically transparent; placing a photoreactivematerial into the container so that said photoreactive material isaccessible by laser light; modifying said photoreactive material bynon-degenerate two-photon absorption.
 2. The method of claim 1, whereinsaid modifying step includes patterned modification to producesolidification of said photoreactive material in accordance with saidpattern.
 3. The method of claim 1, wherein said modifying step includespatterned modification to produce desolidification of said photoreactivematerial in accordance with said pattern.
 4. The method of claim 1,wherein said modifying step includes patterned modification to producemodification of the index of refraction of said photoreactive materialin accordance with said pattern.
 5. The method of claim 1, furthercomprising the steps of: providing an array of controllable pixelelements; directing femtosecond laser pulses onto the array of pixelelements so that said array of pixel elements generates a pulsedpatterned source light having a wavelength selected to inducenon-degenerate two-photon polymerization; providing a first opticalprojection system for projecting said pulsed patterned source light;providing a pulsed laser light having a wavelength selected to inducenon-degenerate two-photon polymerization; providing a second opticalprojection system for projecting said pulsed laser light; synchronizingsaid pulsed patterned laser source light and said pulsed laser light;aiming said pulsed patterned source light so that said pulsed patternedsource light travels through an optically transparent part of saidcontainer into the photoreactive material and focuses inside saidphotoreactive material, forming a first thin, flat sheet of sourcelight; directing picosecond pulsed laser light and focusing saidpicosecond laser pulses into a flat, thin sheet of laser light thatintersects the flat, thin sheet of pulsed patterned source light fromthe array of pixel elements, said intersection creating a fabricationregion, with the respective focal planes of said intersecting sheets oflight overlapping, such that the flat, thin sheet of laser lightintersects the flat, thin sheet of pulsed patterned source lightperpendicular to the projected source so that preselected regions of thephotoreactive material are cured at said fabrication region; directingsaid container having said photoreactive material therein through saidintersecting focal planes at an angle less than the critical angle of amaterial of which said container is made and of said photoreactivematerial; whereby synchronized overlapping pulses operating at twodifferent wavelengths of preselected energies meet the combined energyrequirements necessary to achieve non-degenerate two-photon absorptionin the fabrication region within said photoreactive material.
 6. Themethod of claim 1, further comprising the step of: monitoring real-timevelocity of the container through the fabrication region with a feedbackvelocity-monitoring sensor.
 7. The method of claim 6, further comprisingthe steps of: sending electronic data for each image pattern projectedfrom the controllable pixel element; providing a computer control systemfor throttling the refresh rate of the controllable pixel arrayaccording to velocity feedback data obtained from said velocity monitorsensor.
 8. The method of clam 6, further comprising the steps of:providing a computer control system for altering the conveyor speed inaccordance with velocity feedback data obtained from said velocitymonitor sensor.
 9. The method of claim 6, further comprising the stepsof: providing a computer control system for controlling the laserrepetition rate, the light path length, and the controllable pixel arrayin accordance with velocity feedback data obtained from said velocitymonitor sensor.
 10. The method of claim 6, further comprising the stepof: providing a computer-executable program for extracting a series ofslices of a three-dimensional computer model data into a seriestwo-dimensional image files that are compatible with the controllablepixel elements.
 11. The method of claim 10, further comprising the stepsof: sequentially sending the sequence of two-dimensional imagesextracted from the three-dimensional computer model file to thecontrollable pixel array allowing projection of the slices of thecomputer model file into the photoreactive material as the photoreactivematerial translates through the fabrication region at a velocitydetermined by the photoreactive cure time of the photoreactive materialand the real-time velocity feedback data.